Spatial power combining devices (SPCDs), such as a Qorvo® Spatium® spatial power combining device, utilize a plurality of amplifier assemblies that form a coaxial waveguide to amplify an electromagnetic signal. Each individual amplifier assembly includes an input antipodal finline antenna, an amplifier, and an output antipodal finline antenna. When the amplifier assemblies are combined to form the coaxial waveguide, the input antipodal finline antennas form an input antipodal finline antenna array, and the output antipodal finline antennas form an output finline antenna array.
In operation, an electromagnetic signal is passed through an input port and an input coaxial waveguide section of the spatial power combining device. The input coaxial waveguide section distributes the electromagnetic signal to the input antipodal finline antenna array. Each amplifier amplifies the received signal portion of the electromagnetic signal, and outputs an amplified signal portion via an output antipodal finline antenna. The output antipodal finline antenna array combines the amplified signal portions to form an amplified electromagnetic signal that is passed to an output coaxial waveguide section and then to an output port of the spatial power combining device.
Conventional spatial power combining devices typically use finline antennas. The use of finline antennas has certain drawbacks, including that the printed circuit board (PCB) in which the finline antenna is formed becomes increasingly lossy at higher frequencies. Moreover, a finline antenna requires radio frequency (RF) grounding along its main axis, and thus, the PCB must be solder-attached to the metal body of the amplifier assembly and to the adjacent amplifier assembly. It may be difficult, during assembly of a spatial power combining device, to ensure that the top layer metal of each finline antenna is properly attached to an adjacent amplifier assembly. Failure to properly attach the finline antennas to adjacent amplifier assemblies can result in output power dropouts and amplifier instability.